This specification relates to additive manufacturing, such as fused filament fabrication (FFF) three dimensional (3D) printing.
FFF using extruded polymer filament is useful for manufacturing three dimensional objects. Current FFF printing is typically accomplished by forcing a solid plastic feedstock through a heated nozzle. The filament is liquefied before or as it passes through the constriction in the nozzle, and the feed pressure causes material to be extruded to form a beam of material added, layer by layer, to build the object. 3D models of objects can be designed using computer-aided design (CAD) software and then converted to toolpaths for the nozzle of a 3D extrusion printer, either by the CAD software or separate software, often referred to as a slicer. In addition, various techniques have been employed by slicer software to define tool paths for infill material to be 3D printed inside an object to be manufactured by the 3D printer.